blues books

In my quest to understand and play the blues better, I have been looking for a good blues book for bass. I have one called " Blues Bass, The Complete Method" by Dan Liebman. It seems to be lacking in explaining how the turnaround is built but gives some good examples of bass lines that can be used in jams. I peeked at Ed Friedlands book, "Building Walking Bass Lines" ( I think thats it), but that didnt seem too good for what I am looking for. Does anyone have any suggestions for a good comprehensive book that I can get? Thanks.